The present invention relates to an air intake apparatus for an internal combustion engine, and particularly to an air intake apparatus in which a magnetic inertia effect is employed.
The above-mentioned art is disclosed, for example, in Japanese Patent Application Laid-Open No. 60-224924, Japanese Patent Application Laid-Open No. 6-81719, Japanese Patent Application Laid-Open No. 6-81735, and Japanese Patent Application Laid-Open No. 8-170536.
In the apparatus shown in FIG. 2 of the Japanese Patent Application Laid-Open No. 60-224924, an output torque of the internal combustion engine is increased using the magnetic inertia effect, because the position of an opening to an intake pipe is changed by rotating an approximately cylindrical surge tank and the length of the intake pipe is thus changed.
In the apparatus shown in FIG. 33 of the Japanese Patent Application Laid-Open No. 6-81719 or FIG. 3 of the Japanese Patent Application Laid-Open No. 6-81735, an output torque of the internal combustion engine when rotated in a low speed is increased by providing a to increase the length of an intake pipe by closing a switching valve provided in the middle of the intake pipe when the internal combustion engine rotates at a low speed.
In the apparatus described in the Japanese Patent Application Laid-Open No. 8-170536, two intake pipes of which the length are different from each other are employed and a cylindrical blocking mechanism is provided in the middle of the shorter intake pipe. An output torque of the internal combustion engine is increased by using both of short and long intake pipes to increase the sectional area of a flow passage or by using only the long intake pipe
In the above-mentioned prior art, the length of the intake pipe or the sectional area of its flow passage is changed in order to increase the output torque by using the inertia effect of the intake air to the internal combustion engine. Further, a butterfly valve or a cylindrical switching valve is used to change them.
The apparatus in which the butterfly valve is used has a valve body and a an axis of rotation. These members are made separately and screwed to each other. The axis of rotation is an elongated and rod-shaped member to which a plurality of butterfly valves are fixed. Further, a bearing is provided not only at both ends of the axis of rotation but between the butterfly valves so that the rotation may be not prevent due to the deflection. Because it is necessary to divide the intake pipe into two to install the valve body with such structure and the bearing in the middle of the intake pipe, there is a fear that the dimensional accuracy in assembly is deteriorated.
While, the apparatus in which the cylindrical switching valve is used has an opening penetrating in a radial direction. A valve is formed from the opening and members other than it. An intake air passing through the opening is interrupted by the rotation of the opening. Because the whole periphery of the cylinder forms an axis of rotation in this mechanism, the change in the shape due to deflection is less than that in a butterfly valve. Further, because the axis and the valve can be fabricated in one, there is an advantage that it is easy to fabricate. Further, by using an assembling method in which a hole through which a cylindrical switching valve is inserted in a axial direction is fabricated integrally in a part of the intake pipe of the air intake apparatus, and the cylindrical switching valve is inserted into the hole, it become unnecessary to divide the intake pipe into two as in the case of the butterfly valve. It is, therefore, possible to prevent the deterioration of the dimensional accuracy in a radial direction when assembled.
However, as compared with the apparatus in which the axis of rotation is made of an elongated and rod-like axis member as in the case that the butterfly valve is used, it is necessary to improve a method for fixing in a radial direction in the case that the cylindrical switching valve is used. In the apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-170536, one end of the cylindrical switching valve causes to be contacted on an aperture provided at the bottom of the hole, and it is biased in an axial direction with a spring not so as to it departs from the aperture.
In the above prior art, the relationship between the direction of the axis of rotation of a connection member by which the rotary mechanism for rotating the cylindrical switching valve and the cylindrical switching valve are connected, and the direction of the axis of rotation of the cylindrical switching valve, is not out of consideration. Accordingly, there was possibility that the rotation is not smoothly transmitted when there is displacement or inclination between them.
The present invention can provide an air intake apparatus which can solve the problems which can not be solved in the prior art. Namely, in the present invention, an input shaft which is a member for connecting a cylindrical switching valve and a rotary mechanism together, and the cylindrical switching valve, are brought into contact with each other via a ball-like member. In the above structure, the ball-like member serves as a kind of ball joint, so that rotation can be smoothly transmitted even when there is an angle of inclination between the direction of the axis of rotation of the input shaft by which the rotary mechanism for rotating the cylindrical switching valve and the cylindrical switching valve are connected, and the direction of the axis of rotation of this switching valve.